Furnace for roasting corn flakes or the like loose discrete materials



April 29, 1941. E 0. ENGELS 2,240,291

I FURNACE FOR ROASTING CORN FLAKES OR THE LIKE LOOSE DISCRETE MATERIALS Filed April 1. 1940 0 Slack INVENTOR. EUG'E/VZ' OSWENGZLJ avg ATTORNEY Patented A r. 29, 1941 UNITED. STATES PATENT OFFICE FURNACE FOR ROASTIN G CORN FLAKES OR THE LIKE LOOSE DISCRETE MATERIALS Eugene OscarEngels, Saginaw, Mich., assignor to Baker Perkins, Inc., Saginaw, Mich, a corpora! I tion of New York Application April 1, 1940, Serial No. 337,231

3 Claims.

This invention relates to apparatus for roastmg discrete materials such as cereal flakes, cofiee or cocoa beans, for popping corn, and for like processes in which recirculated hot combustion gases from afurnace are directly applied to the material. It has for its object the provision in combination with the furnace structure of improved means for removing from the recirculated stream of gases inflammable particles such as corn flake fragments, chaff or the like before they are carried into the combustion zone where they would be ignited.

In the instant specification the invention is shown and described as applied to an oven for toasting corn flakes, described in my copending.

descent particles may contaminate or even set fire to the corn flakes or like product being treated. a

As a subordinate feature of the invention, the novel chair-removing device may be combined with the flue and exhaust s'ystemnecessa'ry in closed recirculating heating systems to vent away that proportion of the gaseous stream which is I being replaced by fresh products of combustion from the fuel burner, so that one flue or suction device performs both functions. .Thus it is not periodically necessary to empty a receptacle for the material cleaned fromthe heating gases.

The invention is particularly adapted for use I as an integral part of a recirculating furnace of the kind shown in my United States Patents Nos. 1,857,447, issued May 10, 1932, and 2,110,209, is- -sued March 8, 1938. By utilizing the inherent operation of furnaces of this kind the'necessity for individual separators or screens for cleaning the recirculated gases is eliminated. Specific features and advantages of the invention are further set forth in the following specification.

Referring-to th drawing in which like nu-' merals designate like parts throughout the various views- 1 other end. This for the reason that gases enter-.

ing from duct 5 pass over the opening fastest at Fig. v1 is a diagrammatic end view of a corn flakeroasting oven as shown in my copending point.

application referred to, equipped with two furnaces embodying the invention; Fig. 2 is a top plan view of a furnace of Fig.

.1 partly broken away to show the invention; .and

Fig. 3 is an enlarged vertical cross-section of the furnace taken along lines3-3 'of Fig. 2.

In Fig. 1, numeral l indicates a corn flake toasting oven having two working conveyor runs A, B. Each run is heated by a furnace assembly 3, connected to it by a. supply duct 4 and a return duct 5 for the circulation of hot gases from the furnace. Referring to Figs. 2.and 3,'the furnace 3 consists of an-elongated substantially cylindrical housing 6 containing a coaxially mounted cylindrical combustion chamber 1, at the end of which a fuel burner 8 is mounted.

The return duct 5 is directed tangentially of the housing 6 and is faired into. it spirally, as

shown in Fig. 3, so that the exhaust gases from the oven are directed circumferentially of the combustion chamber 1.

The return gases travel helically around the combustion chamber and at its end are mixed with fresh hot products of combustion from the burner 8. The reheated gases are then driven by an impeller 9 through the return duct 4 to the oven I. i

The construction and operation of the furnace, as so far described, are set forth in my. Patent No. 2,110,209 above referred to. I will .now describe the structure which embodies the inven- I tion.

Approximately ninety degrees from the Vertical axis of the furnace housing 3 (Fig. 3) an elongated slot ill in the jacket 6 extends tran s-,

versely of the return duct 5 and lengthwise of the jacket for the full width of the duct 5 at that upward and inward part way into the annular passage 2 surrounding the combustion chamber 1. In any given furnace baflie II should project a distance determined by the circumferential.

velocity of the gases from return duct 5 and the weight of the'entrained flakes or other particles which are to be removed.

Referring especially to Fig. 2, the baffle llj is' tapered so that its free edge extends inward from-the jacket a distance progressively increasing from that end nearest the burner to its that end nearest the burner, inasmuch as here they travel'substantially circumferentially of the A stationary lip or baffle H extending the length of the lower edge of slot l0, projects Q combustion chamber 6; while toward the opposite end of the opening II, the gases progressively take on a component of helical travel, lengthwise of the combustion chamber 6. Therefore, their circumferential velocity is progressively diminished and the centrifugal force tending to throw entrained flakes or particles outwardly against the housing 3 progressively decreased from the end of bafile II nearest -the burner to the other, that is, from left to right in Fig. 3.

The operation of the separator shown is believed to be self-explanatory. In brief, the gases drawn at high velocity from duct tangentially into the annular passage 2 change their direction so that the heavy particles which are to be separated are thrown outwardly adjacent the wall of the housing and the layer of gas carrying the particles is skimmed off by the baiiie I. The flake particles fall into a suitable receptacle I 2 outside of slot 9. Receptacle II is closed to form a dead air pocket by a bottom gate I3.

Alternatively if desired the bottom of the receptacle I I may be connected by a-duct I4 to a suction.fan I5 which sets up enough suction to remove the particles continuously and also ventirig offthe necessary proportion of the recirculated gases to maintain the desired pressure balance within the system and compensate for the fresh gases introduced by the burner 8. This last construction is illustrated diagrammatically in Figure 3.

The invention affords a particularly simple, in-' expensive, and durable means for effectively re moving all fragments of flakes, chaff or other bits of material which might become charred or ignited if they passed into the furnace beyond the end of the combustion chamber, and thence would return to the oven to contaminate or ignite the corn flakes being treated therein. It is applicable not only to the corn flake toasting apparatus shown and described herein, but also to use wherever furnaces and recirculating systems are employed for roasting cocoa beans, coffee, popping corn, in drying systems, or wherever loose chaff or particles picked up by the gas stream would have undesirable effects if returned to the furnace.

Having'thus described my invention, what I claim and desire to secure by Letters Patent is:

1. ha heating system for toasting or baking light discrete materials by a, recirculated current of hot combustion gases, comprising a furnace having a cylindrical combustion chamber open at one end, a substantially cylindrical jacket surrounding said chamber, spaced therefrom and connected to the baking chamber, aconduit for gases recirculated from the baking chamber tangentially joining said jacket adjacent the burner end of the combustion chamber to direct said recirculated gases circumferentially of the annular passage between said chamber and jacket, in combination, a receptacle outside of said jacket and connected therewith by an opening extending transversely of the said conduit and lengthwise of the jacket wall along a line removed from said return conduit circumferentially of the jacket, and a stationary bafile at an edge of said opening directed slantingly counter to the flow of gases in said annular passage and extending inward a distance sufficient so that flakes or chaff particles entrained in said recirculated gasesand urged centrifugally outward adjacent the jacket wall by their change of direction are intercepted and directed into said receptacle.

2. Apparatus as claimed in claim 1, wherein the stationary bafiie is tapered throughout its length so that it projects progressively farther into the jacket from its end nearest the burner to its other end.

3. In apparatus as claimed in claim 1 wherein a 'major portion only of the recirculated gases from the treating chamber is returned to the furnace, mixed with fresh products ,of combustion and impelled to the treating chamber, the balance of the returned gases being displaced from the system by the fresh products of combustion introduced by the furnace, in combination, suction means connected to the opening in the jacket operable to withdraw the said balance of the returned gases together with the entrained flakes or chaif particles intercepted by said stationary baiiie.

EUGENE OSCAR ENGELs. 

